The Go App downloads the firmware to your phone ready to transfer to drone.
I'm using a Galaxy S5, so I connected my phone to my PC and navigated to \Phone\DJI\dji.pilot\Upgrade\DLPackage
In that folder you should see the latest firmware (if you did the first part of trying to update via the app): P3C_FW_V01.01.0030

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I'm looking for 1.3.2 because a friend has it on his P3S and says he doesn't have the NFZ issues.